Abrasive or refractory articles and method of making the same



Patented Dec. 16, 1930 PRESCOTT HI WALKER AnnsHERMANs. KENYON, or NIAGARA FALLS, NEWYQRK,

ASSIGNORS TO THE CARBORUNDUM COMPANYQOE N IAGARAFALLS, NEW YORK, A.

CORPORATION OF PENNSYLVANIA 'ABRASIVE on REFRACTORY ARTICLES AND METHOD or MAKING THE SAME This invention relates to an improved abrasive, refractory or other article made of a granular substance bonded with? suitable bind-er, more particularly a vitrlfied or cethem.

In the dressing of abrasive wheels, some of quently such trueing devices have been no harder' and Wear-"resistant than the hardest abrasive wheels. Therefore, the'use' 'ofsuch a device for trueing the grinding-face of a Wheel is only partially satisfactory because excessive W831i"HlakGS llTlIIIPOSSIblG to produce.

a grinding surface of the des'ired truth, shape or degree of sharpness.

Likewise, refractory ofvvhich they areused,'will have an increased life if they are less permeable, the-life of re fractories being "more 0 their permeability ticles and,-at the sametime,modifyorireinforce the binder or union betweenthe bmder and the i granular materials ,in such v manner. that the abrasive or refractory article is ex-@ tremely: wear resistant and I has -110W per neuabilitya An abrasive-articlemade in accord; ance with our invention can be used with;

u h: greater e qien y' a e r eine Q1. d

s- 0 Drier. e her SHHPQSQSWIIQIQ a e rem l' hard (Wear, r is nta q sie a cle is required. 1 Not all: methodslof decreasing.

thepermeabilityof an abrasive article have properties FOrinstancdithas heretofore ramic binder, and to amethod of producing articles such as refract'ory"bricksand shapes," and more particularly refractory'articles composedofsubstances which are oxidized, decomposed ore attacked byfurnace gases in the presence r less proportional to 'i l id e f tee i besa' the d nsit of the composit oncan be decreased Without necessarily ncreasing its Wear reslstant :11 Application mam .1, 19281 Serial No. 2 74,352.

of low permeability. Such'an article, jhoi'v ever, inaynot be highly Wear resistant'and in the case of an abrasive article is no more" or but little more abrasive than those of the usual nature. Some suchrefractory, articles may not be highly Wear resistant because of" the possible 'weakening effect 'on the bond' due to the oxidation of the fine'particlesl,

According to our invention, it is proposed to decrease the permeability of an article granular substance "by" formed of a bonded applying thereto some materialwhich will impregnate the porous article and which Will, itself,or some resultant fproductthereof, be interstitially deposited either by chemical action or by addition or removal of heat, or combinations 'of such methods that the pro-c,

'cess will tend to fill the poreso'f the article or augment the binding properties of thebond and thus render "the artiele'less permeable andmoreresistant. An. example of a satisfactory method of decreasing permeability is the impregnation f of abondedabrasive article with a'binder'inf liquid form, and'the consequent settingof the binder. We have fOundthatQsuch materials as aluminum hydroxide and calcium 'hy V droxid'e decrease the permeability'satisfac According-to-the=present invention -1t 1s proposed to increasethedensity or lessen the; permeability of abrasive and refractory artorily when they are deposited in situ and the product subsequently burned. Other ina-f terials, such as alkali silicate solutions, orclay suspensions, or solutions of salts may be used todecre'ase the permeability. p 'As a'specific example of the invention, a. bonded abrasive wheel or stick used for 'dress- I ing abrasive Wheels is" impregnated time saturated solution 'of aluminum chloride and calciumchloride in the meter ten parts or aluminum chloride; to one part of calcium ch1 'ride.j .T11e hydroxides of aluminum and calciumare then precipitated f in the ores of: the article by immersion of the article in and v monium'ihydrox'ide or by exposure ofthe article to ammonia'vap'ors. "The article is then baked "or: burned tocondition it. l 'It has been found that an abrasive Wheel or stick use d for dressing abrasive vvlieelsj treated in this "mannerfwill have itsresiistance to wear increased five 'or nofre times over that of the usualarticles' made for the ur ose and its permeability decreased greatly, sometimes as much as or more. While the invention, as applied to abrasive articles, is particularly applicable to wheel trueing devices, it is also useful in the more common abrasive articles.

In the copending application of F. J. Tone, Serial Number 212,189, filed August 10, 1927, for a Low permeable refractory, and in the copending application of Be-nner and Easter, Serial No. 181,602, filed April 6, 1927, for improvement in Refractory articles and furnace lining made therefrom, certain methods are disclosed for increasing the density of refractories, including both aluminum oxide and silicon carbide refractories, but more particularly those refractories which are composed of substances which are oxidized, decomposed or attack-ed by the furnace gases to which they are exposed in use. It is pointed out in the said applications that the life of these refractories is more or less proportional to the permeability thereof.

The present invention may be used either alone or in conjunction Vii/l1 the processes of said copending applications to render a bonded granular article used as an abrasive much less permeable.

The article may be treated, as heretofore described in connection with abrasive articles. We prefer, however, in the treatment of refractories, particularly aluminum oxide refractories, to impregnate the bonded refractory article, either by painting or by dipping with a decomposable salt, such as a solution of aluminum sulphate. The impregnated article is then heated, either by a special heating operation or upon the first firing of the furnace in which the refractory is used, to a temperature approximating 800 C. The aluminum sulphate is decomposed and aluminum oxide is deposited in the pores of the brick in an extremely satisfactory manner.

The advantages of the invention reside in the fact that the permeability of the bonded granular article can be decreased greatly, sometimes 100% or more, and the article made hi hly wear resistant. Articles produced in accordance herewith have a permeability of less than 50 cubic centimeters. The invention can also be applied'to an article composed of pulverant material and a binder and the advantages of the invention secured.

The permeability is measured according to any suitable method, that disclosed in said Benner and Easter application Serial No. 181,602, preferably being employed. According to this method, air at a known pressure is applied to one face of the article to be tested and allowed to escape from the op posite face, the others being sealed by immersion in mercury. The air flow through the specimen is then measured by a meter in the air line ahead of the article. By multiplying the observed flow by the thickness of the ticular materials nor the exact method described, as various changes and modifica tions may be made therein to secure the same advantages and such changes and modifications are within the contemplation of our invention.

\Ve claim:

1. An abrasive article comprised of granular material and a binder, and having a filler in the pore space thereof substantially throughout the mass and having a per1neability less than fifty cubic centimeters.

2. An article composed of granular abrasive particles and a binder, and having metallic oxide in the pores thereof distinct from the binder.

3. A ceramic article of low permeability comprising bonded granular particles and a non-oxidizable filling in the pores thereof throughout the mass, which filling is independent of and distinct from the medium which bonds the particles.

i. A bonded ceramic article of low permeability comprising a burned mass of granular particles and a binder, the pores substantially throughout the mass containing a heat resistant material which is distinct from the binder.

5. A method of producingceramic articles of low permeability which consists in forming a bonded article of granular material and a binder, and then filling the pores of the article throughout the mass with an inorganic heat resistant substance distinct from the binder.

6. A method of producing ceramic articles of low permeability which consists in forming and maturing a bonded article of granular material and a binder, and then filling the pores substantially throughout the mass with a filler, and thereafter heating the article.

7. A method of producing ceramic articles of low permeability which consists in forming a bonded article of comminuted material and a binder, and then filling the pores substantially throughout the mass with a heat resistant oxide distinct from the binder.

8. The method of producing a ceramic article of low permeability which consists in forming aporous ceramic bonded article, filling the pores of said article with a fluid material and then decomposing the material 1 article.

.1 cipitating an insoluble filler within the pores, and thereafter heating the 9. Amethod of producing a ceramic article of low permeability which consists in first forming and firing a porous ceramic article, then impregnating the pores of the article throughout substantially its entire mass with a fluid, and then treating the fluid material to efl'ect a change therein to form a filler within the pores of the article.

10. A method of producing a ceramic article of low permeability which consists in first forming and firing a porous ceramic article containing granular material and a bond, then impregnating the article with a decomposable salt, then baking the article to eifect a change in the decomposable material.

11. A method of producinga ceramic article of low permeability which consists in forming and maturing a bonded ceramic article, impregnating the pores of the article throughout substantially its entire mass with an aluminum salt, and then converting the salt into a non-soluble material.

12. A method of producinga ceramic article of low permeability which consists in first forming a bonded ceramic article, impregnating the article with a saltin solution, and then converting the salt into a non-soluble substance in situwithin the pores of the article, and thereafter heating the article- 13. A method of producing a ceramic article of low permeability which consists in impregnating the pores of the formed and matured bonded article throughout substantially its entire mass with a soluble material, then converting the soluble material in situ into a non-soluble filler. V

14. A bonded and matured ceramic article comprised of grains and a bond having a filler distinct from the bond in the pores thereof formed from a decomposable salt which has been subjected to the action of heat.

15. A bonded and matured ceramic article comprised of grains and a bond having a filling material in the pores thereof comprised of a substance distinct from the bond precipitated in situ in the article.

16. The method of making a low permeable Q article comprised of granular material and a bond which comprises forming the article from the granular material and a bond, maturing the bond, thereafter impregnating the article with a soluble salt, precipitating an insoluble material in situ within the pores of the article from said salt and thereafter dehydrating the precipitate.

17. The method of reducing the perme-' ability of a matured ceramic article containing granular material which comprises immersing the article in a solution containing aluminum and calcium salts, thereafter presolution in situ in the pore spaces of the article, and thereafter heating the article to dehydrate the precipitated filler.

18. A hard abrasive article comprising bonded abrasive grains and a hard refractory material in the space between the bonded grains, said hard refractory material being formed in situ after the primary bonding whereby the density and hardness of the abrasive article are increased, the refractory material being distinct from the primary bonding agent.

19. The process of increasing the hardness and density of a bonded abrasive article which comprises immersing the article in a solution of a salt, precipitating a hydrate of said element by'means of an ammonium compound in the pores of the article, and dehydrating the precipitate by the application of heat.

In testimony whereof We'have hereunto set our hands.

PRESCOTT H. WALKER. SHERMAN S. KENYON.

from the salt 7 

